Climate driven variability in the demography and physiology of the Uinta ground squirrel

2018 Summer.Includes bibliographical references.Climate change is impacting the phenology of many species, ultimately altering their fitness and population dynamics. Shifts in phenology have been documented across a variety of taxa and ecosystems, but few studies have considered the effects of pertinent season-specific climatic variables on phenology and fitness. Hibernators may be particularly susceptible to changes in climate since they have a relatively short active season in which to reproduce and gain enough mass to survive the following winter. To understand whether and how climatic changes may be affecting hibernator fitness, we analyzed historical (1964-1968) and contemporary (2014-2017) mark-recapture data taken from the same population of Uinta ground squirrels (UGS, Urocitellus armatus). Although survival of UGS has not changed significantly over time, annual survival seems to fluctuate strongly in response to climate and phenology. Population density also increased, suggesting resources are less limited today than they used to be. Cheatgrass is now dominating low-elevation UGS habitat and seems to provide a better food source than native plants did historically. Although the phenology of UGS has not changed significantly over time with a locally warming climate (3.22ºF over 50 years), season-specific climatic variables were important in determining over-winter survival rates. To understand the role that physiological processes play in shaping the life history of UGS in light of warming temperatures, we studied UGS life history trade-offs near the extremes of their elevation range (6200 ft. versus 8000 ft.) which offer contrasted micro-climatic conditions. Specifically, we quantified trade-offs between body mass dynamics and immune function in two populations of UGS that experience different phenologies and active season lengths. UGS at the high elevation had a shorter active season, largely driven by extended snow cover into spring. UGS at this elevation also weighed less at emergence from hibernation than UGS at the lower elevation. Despite this, UGS at the high elevation gained mass faster than UGS at the low elevation, entering estivation at a similar weight. This accelerated mass gain was associated with a decline in immune function at the higher elevation, but not at the lower elevation where UGS experience a much longer active season and are not food-limited. Juveniles generally gained mass faster than adults and yearlings, but did not demonstrate a decrease in immune function at either elevation, possibly because they do not have to bear the energetic burden of reproduction. Our results improve our understanding of how hibernators respond to climate change, and how these plastic responses lead to contrasted life history strategies. Our results have implications for the conservation of this species and similar ones that are sensitive and responsive to even small changes in climate

Author Correction: Ecology, evolution and spillover of coronaviruses from bats.

In the past two decades, three coronaviruses with ancestral origins in bats have emerged and caused widespread outbreaks in humans, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the first SARS epidemic in 2002–2003, the appreciation of bats as key hosts of zoonotic coronaviruses has advanced rapidly. More than 4,000 coronavirus sequences from 14 bat families have been identified, yet the true diversity of bat coronaviruses is probably much greater. Given that bats are the likely evolutionary source for several human coronaviruses, including strains that cause mild upper respiratory tract disease, their role in historic and future pandemics requires ongoing investigation. We review and integrate information on bat–coronavirus interactions at the molecular, tissue, host and population levels. We identify critical gaps in knowledge of bat coronaviruses, which relate to spillover and pandemic risk, including the pathways to zoonotic spillover, the infection dynamics within bat reservoir hosts, the role of prior adaptation in intermediate hosts for zoonotic transmission and the viral genotypes or traits that predict zoonotic capacity and pandemic potential. Filling these knowledge gaps may help prevent the next pandemic

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Data from: Seasonal climate effects on the survival of a hibernating mammal

Global climate change and associated regional climate variability is impacting the phenology of many species, ultimately altering individual fitness and population dynamics. Yet, few studies have considered the effects of pertinent seasonal climate variability on phenology and fitness. Hibernators may be particularly susceptible to changes in seasonal climate since they have a relatively short active season in which to reproduce and gain enough mass to survive the following winter. To understand whether and how seasonal climate variability may be affecting hibernator fitness, we estimated survival from historical (1964-1968) and contemporary (2014-2017) mark-recapture data collected from the same population of Uinta ground squirrels (UGS, Urocitellus armatus), a hibernator endemic to the western United States. Despite a locally warming climate, the phenology of UGS did not change over time, yet season-specific climatic variables were important in regulating survival rates. Specifically, older age classes experienced lower survival when winters or the following spring were warm, while juveniles benefited from warmer winter temperatures. Although metabolic costs decrease with decreasing temperature in the hibernacula, arousal costs increase with decreasing temperature. Our results suggest that this trade-off is experienced differently by immature and mature individuals. We also observed an increase in population density during that time period, suggesting resources are less limited today than they used to be. Cheatgrass is now dominating the study site and may provide a better food source to UGS than native plants did historically

Morphological and quantitative analysis of leukocytes in free-living Australian black flying foxes (Pteropus alecto).

The black flying fox (Pteropus alecto) is a natural reservoir for Hendra virus, a paramyxovirus that causes fatal infections in humans and horses in Australia. Increased excretion of Hendra virus by flying foxes has been hypothesized to be associated with physiological or energetic stress in the reservoir hosts. The objective of this study was to explore the leukocyte profiles of wild-caught P. alecto, with a focus on describing the morphology of each cell type to facilitate identification for clinical purposes and future virus spillover research. To this end, we have created an atlas of images displaying the commonly observed morphological variations across each cell type. We provide quantitative and morphological information regarding the leukocyte profiles in bats captured at two roost sites located in Redcliffe and Toowoomba, Queensland, Australia, over the course of two years. We examined the morphology of leukocytes, platelets, and erythrocytes of P. alecto using cytochemical staining and characterization of blood films through light microscopy. Leukocyte profiles were broadly consistent with previous studies of P. alecto and other Pteropus species. A small proportion of individual samples presented evidence of hemoparasitic infection or leukocyte morphological traits that are relevant for future research on bat health, including unique large granular lymphocytes. Considering hematology is done by visual inspection of blood smears, examples of the varied cell morphologies are included as a visual guide. To the best of our knowledge, this study provides the first qualitative assessment of P. alecto leukocytes, as well as the first set of published hematology reference images for this species

Ecology, evolution and spillover of coronaviruses from bats.

In the past two decades, three coronaviruses with ancestral origins in bats have emerged and caused widespread outbreaks in humans, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the first SARS epidemic in 2002-2003, the appreciation of bats as key hosts of zoonotic coronaviruses has advanced rapidly. More than 4,000 coronavirus sequences from 14 bat families have been identified, yet the true diversity of bat coronaviruses is probably much greater. Given that bats are the likely evolutionary source for several human coronaviruses, including strains that cause mild upper respiratory tract disease, their role in historic and future pandemics requires ongoing investigation. We review and integrate information on bat-coronavirus interactions at the molecular, tissue, host and population levels. We identify critical gaps in knowledge of bat coronaviruses, which relate to spillover and pandemic risk, including the pathways to zoonotic spillover, the infection dynamics within bat reservoir hosts, the role of prior adaptation in intermediate hosts for zoonotic transmission and the viral genotypes or traits that predict zoonotic capacity and pandemic potential. Filling these knowledge gaps may help prevent the next pandemic